class AwaitReader {
    output: TextBlock
    status: TextBlock
    task: Object
    file: Object
    response: String
    function apply(self: AwaitReader): String {
        self.response = await self.file
        self.output.text = "读取完成；在 REPL 查看 reader.response 或 reader.task.result()"
        return self.response
    }
    function read(self: AwaitReader, path: String): Unit {
        self.file = ui.readText(self, "file", path)
        self.task = ui.spawn(self, "workflow", self.apply)
        self.response = ""
        self.output.text = "等待文件"
        self.status.bind("text", self.task.status)
    }
}
output = TextBlock("在 REPL 调用 reader.read(绝对路径字符串)")
status = TextBlock("")
reader = AwaitReader(output,status,ui.state(0),ui.state(0),"")
page = Page()
page.title = "await 文件"
page.render(Column(24,16,status,output))